Happy to say https://indieauth.com is now running on 3 physically separate servers behind DNS load balancing!
Took quite a bit of refactoring to make the three servers not require a shared backend. Lots of taking advantage of storing state "on the wire" rather than in a database. If you notice any weirdness or glitches, definitely let me know!
If you'd like to volunteer a server to help share the load, let me know. It requires Nginx, Ruby, Redis and Memcache.